Just like any other image viewer, Google Photos has always supported pinch-to-zoom on images. You've never been able to zoom in on videos, though — that long-requested ability is absent from Google's software. Now, the first evidence has surfaced that the company is working on this functionality.
XDA Developers managed to activate the zoom gesture for videos by tinkering with the Photos app. It's simple enough to use: Just pinch your fingers as you would on images to have a closer look at something. You can even move around in the scene. A GIF probably serves best to demonstrate this:
At the moment, the feature isn't officially available in any public-facing release of Google Photos. It might still be a good idea to use the latest version of the app when Google enables the zoom gesture via a server-side switch at some point in the future.
- XDA Developers